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18 Cards in this Set
- Front
- Back
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temperature
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=energy of motion of atoms/molecules of an object
absolute zero=temp at which all motion ceases. (0 K, -273 C, -459 F) |
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wavelegnth
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legnth over which wave repeats in pattern (meters)
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frequency
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how often the wave repeats itself (cycles per second)
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speed=
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wavelegnth times frequency
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electromagnetic spectrum
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radio, infrared, visible, ultraviolet, x-ray, gamma ray
(left to right) frequency increases, wavelegnth decreases |
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the hotter the object..
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-> higher temp -> faster the particles move -> more energy they radiate
(more intensely it radiates energy) |
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blackbody curve
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=distribution of reemitted radiation; in steady state, (when T is contant), blackbody must reemit same amount of energy it absorbs
curve shifts toward higher frequencies (shorter wavelegnths) and greater intensities as the object's temp increases |
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stefan-boltzmann law
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intensity of light is directly related to temp of the object to the fourth power
intensity= T^4 |
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wien's law
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wavelegnth of peak emission= 1/T
the hotter an object, the bluer its radiation/ the shorter its wavelegnth |
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continuous spectra
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covers full range of wavelegnths
rainbow running from red to violet w/out interruption. |
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emission spectra
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pattern of spectral emission lines that represent emission at only certain wavelengths
hot,low density gas |
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absorption spectra
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certain wavelegnths missing; dar lines in otherwise continuous bright spectrum, where light w/in 1 narrow frequency range has been removed
cool, low density gas |
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model of atom
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nucleus=core
protons=positive; # determines what element it is neutrons=neutral; # determines what isotope the element is electrons=negative; orbit the nucleus |
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why movement of electrons around nucleus cause atom to absorb/emit enegery?
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1.opposites attract
2.discrete levels; different electrons have different allowed electron levels. closest are in ground state 3.discrete energy levels 4.when electron absorbs enough energy, can pull away- ion |
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energy levels
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if low energy photon strikes electron, it is absorbed and electron jumps up 1 level
higher energy photon will cause electron to jump 2 levels higher energy of photon=higher jump electron in higher levels= excited (but wants to go back into ground state) |
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hydrogen spectra
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hydrogen= most abundant element in universe; simplest atom
lyman series:91-122 nm (UV) balmer series:365-656 nm (visible and UV) paschen series:820-1875 nm (IR) |
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doppler effect
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observer in front of source: shorter wavelegnths, blueshifted
observer in back of source: longer wavelegnths, redshifted |
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blueshift/redshift
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blueshift: shift towards blue (shorter wavelegnths)due to object moving towards us
redshift: shift towards red end of spectrum (longer wavelengths) |
